The Usefulness of In Vitro Percutaneous Absorption Experiments Applying the Infinite Dose Technique to Predict In Vivo Plasma Levels: Comparison of Model-Predicted and Observed Plasma Concentrations of Nortriptyline in Rats.

The aims of this study were to evaluate the feasibility of a nortriptyline (NT) formulation for transdermal administration and to assess the usefulness of an estimated kinetic parameter (kout) using the in vitro infinite dose technique to predict in vivo plasma levels when used in combination with pharmacokinetic parameters. To do so, a simple one-compartment model was used to describe the transport of a permeant across a membrane (skin). This model provides relatively simple expressions for the amount of permeant in the skin, the cumulative amount of permeant that crosses the skin, and the flux of permeant, for both the infinite and the finite dose regimens. Transdermal administration of the formulated NT gel to rats resulted in plasma levels of approximately 150 ng/mL between 8 and 30 h post-administration. These levels were higher than the minimum concentration of 40 ng/mL recommended for smoking cessation therapy and slightly higher than the upper limit of the therapeutic range for the treatment of depression in humans. The one-compartment model used to describe transport across the skin was connected to a two-compartment pharmacokinetic model used to predict NT plasma concentrations in rats using the kout determined in vitro and the values of other pharmacokinetic parameters obtained in vivo. The predicted concentrations were close to the observed plasma levels and the time profiles were similar for both types of data. These results show the usefulness of the kout parameter determined in vitro to predict plasma concentrations of drugs administered percutaneously.

MUC1 intracellular bioactivation mediates lung fibrosis.

BACKGROUND: Serum KL6/mucin 1 (MUC1) has been identified as a potential biomarker in idiopathic pulmonary fibrosis (IPF), but the role of MUC1 intracellular bioactivation in IPF is unknown. OBJECTIVE: To characterise MUC1 intracellular bioactivation in IPF. METHODS AND RESULTS: The expression and phosphorylation of Thr41 and Tyr46 on the intracellular MUC1-cytoplasmic tail (CT) was increased in patients with IPF (n=22) compared with healthy subjects (n=21) and localised to fibroblasts and hyperplastic alveolar type II cells. Transforming growth factor (TGF)-ß1 phosphorylated SMAD3 and thereby increased the phosphorylation of MUC1-CT Thr41 and Tyr46 in lung fibroblasts and alveolar type II cells, activating ß-catenin to form a phospho-Smad3/MUC1-CT and MUC1-CT/ß-catenin nuclear complex. This nuclear complex promoted alveolar epithelial type II and fibroblast to myofibroblast transitions, as well as cell senescence and fibroblast proliferation. The inhibition of MUC1-CT nuclear translocation using the inhibitor, GO-201 or silencing MUC1 by siRNA, reduced myofibroblast transition, senescence and proliferation in vitro. Bleomycin-induced lung fibrosis was reduced in mice treated with GO-201 and in MUC1-knockout mice. The profibrotic lectin, galectin-3, directly activated MUC1-CT and served as a bridge between the TGF-ß receptor and the MUC1-C domain, indicating TGF-ß1-dependent and TGF-ß1-independent intracellular bioactivation of MUC1. CONCLUSIONS: MUC1 intracellular bioactivation is enhanced in IPF and promotes fibrotic processes that could represent potential druggable targets for IPF.

Evaluation of bleeding risk and measurement methods in dental patients

Objective: The present study explores bleeding manifestations in routine dental surgical procedures, evaluates the influence of antithrombotic drugs upon bleeding risk, and validates the efficiency of a clinical method for the measurement of bleeding.Material and method: A prospective observational study was made involving a cohort of 99 patients in the setting of normal clinical practice, with the added conduction of prior hematological tests including baseline hemostasis and platelet function, based on a new method (Multiplate System(R). For evaluation of the bleeding manifestations,a clinical method was selected that evaluates bleeding on the basis of its duration and the hemostatic measures needed to resolve the problem.Results: Almost one-third of the patients (27.3%) were receiving treatment with oral antiplatelet drugs, while 19.2% received oral anticoagulants and 9% received combined therapy with acetylsalicylic acid plus clopidogrel. In turn, an 8% incidence of moderate bleeding episodes was detected correlated to the ASPI platelet function testand to advanced patient age.Conclusion: The incorporation of platelet function tests increases the safety of oral surgery in elderly patients subjected to antiplatelet treatment, particularly with acetylsalicylic acid and clopidogrel (AU)

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Evaluation of bleeding risk and measurement methods in dental patients.

OBJECTIVE: The present study explores bleeding manifestations in routine dental surgical procedures, evaluates the influence of antithrombotic drugs upon bleeding risk, and validates the efficiency of a clinical method for the measurement of bleeding. MATERIAL AND METHOD: A prospective observational study was made involving a cohort of 99 patients in the setting of normal clinical practice, with the added conduction of prior hematological tests including baseline hemostasis and platelet function, based on a new method (Multiplate System®). For evaluation of the bleeding manifestations, a clinical method was selected that evaluates bleeding on the basis of its duration and the hemostatic measures needed to resolve the problem. RESULTS: Almost one-third of the patients (27.3%) were receiving treatment with oral antiplatelet drugs, while 19.2% received oral anticoagulants and 9% received combined therapy with acetylsalicylic acid plus clopidogrel. In turn, an 8% incidence of moderate bleeding episodes was detected correlated to the ASPI platelet function test and to advanced patient age. CONCLUSION: The incorporation of platelet function tests increases the safety of oral surgery in elderly patients subjected to antiplatelet treatment, particularly with acetylsalicylic acid and clopidogrel.

Quantification of nortriptyline in plasma by HPLC and fluorescence detection.

A simple, sensitive and specific high-performance liquid chromatography method has been developed for the determination of nortriptyline (NT) in plasma samples. The assay involved derivatization with 9H-fluoren-9-ylmethyl chloroformate (Fmoc-Cl) and isocratic reversed-phase (C(18)) chromatography with fluorescence detection. The developed method required only 100 microl of plasma sample, deproteinized and derivatized in one step. Calibration curves were lineal over the concentration range of 5-5000 ng/ml. The derivatization reaction was performed at room temperature in 20 min and the obtained NT derivative was stable for at least 48 h at room temperature. The within-day and between-day relative standard deviation was below 8%. The limit of detection (LOD) was 2 ng/ml, and the lower limit of quantification (LLOQ) was established at 10 ng/ml. The method was applied on plasma collected from rats, at different time intervals, after intravenous administration of 0.5 mg of NT.

[Recommendations for antibiotic monitoring in ICU patients]. / Recomendaciones para la monitorización de antibióticos en pacientes críticos ingresados en UCI.

Monitoring plasma concentrations of antimicrobial agents used to treat infection in critically ill patients is one of the recommended strategies for improving clinical outcome. Drug monitoring has a double aim: to limit adverse events and to increase the effectiveness of the drugs. In clinical practice, however, this approach is mainly limited to monitoring plasma concentrations of vancomycin and aminoglycosides, although future extension to other antimicrobial agents would be desirable. Application of this technique varies considerably between hospitals, and this makes interpretation and comparison of the results obtained difficult. For this reason, representatives of various scientific societies related to the pharmacokinetic area have developed a series of recommendations for monitoring plasma concentrations of antimicrobials using vancomycin and several aminoglycosides as the reference. The recommendations are based on 14 questions encompassing all steps of the process: indication for the test, blood sampling (timing of blood collection, blood volume, tubes), transport to the laboratory, techniques applied, normal values, dose adjustment, and reporting the results. The purpose of these guidelines is to develop a process of monitoring plasma antimicrobial concentrations that is as homogeneous as possible to facilitate the design of multicenter studies, as well as the interpretation and comparison of results.

[Recommendations for antibiotic monitoring in ICU patients]. / Recomendaciones para la monitorización de antibióticos en pacientes críticos ingresados en UCI.

UNLABELLED: Monitoring plasma concentrations of antimicrobial agents used to treat infection in critically ill patients is one of the recommended strategies for improving clinical outcome. Drug monitoring has a double AIM: to limit adverse events and to increase the effectiveness of the drugs. In clinical practice, however, this approach is mainly limited to monitoring plasma concentrations of vancomycin and aminoglycosides, although future extension to other antimicrobial agents would be desirable. Application of this technique varies considerably between hospitals, and this makes interpretation and comparison of the results obtained difficult. For this reason, representatives of various scientific societies related to the pharmacokinetic area have developed a series of recommendations for monitoring plasma concentrations of antimicrobials using vancomycin and several aminoglycosides as the reference. The recommendations are based on 14 questions encompassing all steps of the process: indication for the test, blood sampling (timing of blood collection, blood volume, tubes), transport to the laboratory, techniques applied, normal values, dose adjustment, and reporting the RESULTS: The purpose of these guidelines is to develop a process of monitoring plasma antimicrobial concentrations that is as homogeneous as possible to facilitate the design of multicenter studies, as well as the interpretation and comparison of results.

Recomendaciones para la monitorización de antibióticos en pacientes críticos ingresados en UCI / Recommendations for antibiotic monitoring in ICU patients

La monitorización de concentraciones plasmáticas de los antimicrobianos utilizados para el tratamiento de infecciones en pacientes críticos es una de las estrategias planteadas para mejorar los resultados clínicos. El objetivo de la monitorización es doble: limitar los efectos adversos y aumentar la efectividad de los antimicrobianos. Su desarrollo clínico se limita prácticamente a la monitorización de vancomicina y aminoglucósidos, aunque es deseable su extensión, en el futuro, al resto de antimicrobianos. La aplicación de esta técnica está sometida a múltiples variaciones entre hospitales, lo que dificulta la interpretación y comparación de resultados. Por este motivo, representantes de diversas sociedades científicas relacionadas con el área de la farmacocinética han elaborado un conjunto de recomendaciones para la monitorización plasmática de antimicrobianos utilizando como referencia la vancomicina y los distintos aminoglucósidos. La recomendaciones se realizan en torno a 14 preguntas que abarcan todas las etapas de proceso: indicación de la prueba, extracción de la muestra (tiempo de extracción, cantidad de sangre, tubos), traslado al laboratorio, técnicas aplicables, valores de normalidad, ajuste de dosis y comunicación de resultados. El objetivo de las recomendaciones es homogeneizar en la medida de lo posible el proceso de la monitorización de estos antimicrobianos y facilitar con ello la realización de estudios multicéntricos y la comparación e interpretación de los resultados (AU)

Monitoring plasma concentrations of antimicrobial agents used to treat infection in critically ill patients is one of the recommended strategies for improving clinical outcome. Drug monitoring has a double aim: to limit adverse events and to increase the effectiveness of the drugs. In clinical practice, however, this approach is mainly limited to monitoring plasma concentrations of vancomycin and aminoglycosides, although future extension to other antimicrobial agents would be desirable. Application of this technique varies considerably between hospitals, and this makes interpretation and comparison of the results obtained difficult. For this reason, representatives of various scientific societies related to the pharmacokinetic area have developed a series of recommendations for monitoring plasma concentrations of antimicrobials using vancomycin and several aminoglycosides as the reference. The recommendations are based on 14 questions encompassing all steps of the process: indication for the test, blood sampling (timing of blood collection, blood volume, tubes), transport to the laboratory, techniques applied, normal values, dose adjustment, and reporting the results. The purpose of these guidelines is to develop a process of monitoring plasma antimicrobial concentrations that is as homogeneous as possible to facilitate the design of multicenter studies, as well as the interpretation and comparison of results (AU)

Effect of intracerebroventricular continuous infusion of valproic acid versus single i.p. and i.c.v. injections in the amygdala kindling epilepsy model.

Two protocols were tested to assess anticonvulsant efficacy and drug concentrations after intracerebroventricular (i.c.v.) continuous valproic acid (VPA) infusion, as compared with acute injections in the kindling epilepsy model. Protocol 1: amygdala-kindled rats were injected via intraperitoneal (i.p.) and i.c.v. routes with varying doses of VPA and tested for seizure intensity, afterdischarge and seizure duration, ataxia and sedation. Concentrations of VPA were determined by immunofluorescence in the brain, plasma, cerebrospinal fluid (CSF) and liver in matching rats. Protocol 2: amygdala-kindled rats were implanted with osmotic minipumps containing a VPA solution in saline and connected to intraventricular catheters for 7 days. Seizure threshold, latency and duration, afterdischarge duration, ataxia and sedation were recorded daily before, during, and until 5 days after VPA infusion. In matching animals, CSF, brain, plasma and liver VPA concentration was determined. Acute i.c.v. VPA injection suppressed seizures with a remarkable ataxia and sedation. However, continuous i.c.v. infusion controlled generalised and even focal seizures without producing important side effects, high plasma levels or hepatic drug concentrations. In conclusion, continuous i.c.v. VPA infusion may protect against kindled seizures by minimising ataxia and sedation, and achieving suitable intracerebral, yet low plasma or hepatic drug concentrations, thus avoiding potential systemic toxicity.